1. Field of the Invention
The present invention relates to a lens-interchangeable camera and a method of controlling the same.
2. Description of the Related Art
An image recovery algorithm is known to recover an image that is obtained by an image capturing apparatus such as a digital still camera and degraded due to aberration or the like. As the image recovery algorithm, a method is known which, for example, expresses an image degradation characteristic as a point spread function (to be referred to as a PSF hereinafter), and recovers an image to a degradation-free image based on the PSF. As such an algorithm, for example, Japanese Patent Laid-Open No. 62-127976 discloses a method of correcting a blur using a filter with a characteristic opposite to the PSF. Japanese Patent Laid-Open No. 2004-205802 discloses a method of generating a Wiener filter from a PSF and recovering a degraded image using the Wiener filter. A recovery process filter expressed by a Wiener filter is given byOTF(u,v)/(|OTF(u,v)|2+c)  (1)where OTF (u,v) is an optical transfer function (to be referred to as an OTF hereinafter) at a frequency u in the x direction and a frequency v in the y direction, and c is a constant having a very small value. When performing image recovery processing using a real space filter, the Wiener filter obtained by expression (1) is returned to a real space filter by inverse Fourier transformation and then applied.
In addition, Japanese Patent Laid-Open Nos. 11-112859, 2008-92000, and 2008-92001 disclose techniques of performing correction according to optical characteristics unique to a lens, although no specific filtering schemes are mentioned.
Ideally, a recovery filter optimum for capturing conditions is used. However, creating a recovery filter every time the capturing conditions change is very expensive. Additionally, although the amount of OTF data necessary for filter creation is very large, the communication speed between the lens and the camera is very low. To hold recovery filters for every capturing condition in a memory in advance, the memory requires a very large capacity. Hence, a method needs to be devised to decrease the communication data amount by creating a recovery filter on the lens side and transmitting/receiving only filter data between the lens and the camera, and also reduce the load of recovery filter creation on the lens side.